1. Field of the Invention
The invention relates to the art of metal shaping and more particularly to roll-forming apparatus for manufacturing roll-formed configurations for special applications and may be used for making articles from a workpiece having cross-sectional configurations varying lengthwise thereof.
2. Description of the Prior Art
In modern practice roll-formed sections are made in roll-forming machines from a workpiece having a constant cross-sectional configuration lengthwise thereof and made of unsorted and low-alloyed steels in by-the-piece manufacturing processes as well as by-the-roll and continuous processes. Conventional roll-forming machines do not provide for making special-purpose sections from a workpiece having cross-sectional configurations varying lengthwise thereof. Such sections are useful, for example, in producing support members forming part of automotive frames. The problem involved in roll-forming machines stem from a need to produce roll-formed articles having cross-sectional configurations varying lengthwise thereof from work-pieces of various steels and having various thicknesses and at the same time having cross-sectional configurations that vary lengthwise thereof.
Known in the art is a roll-forming machine (U.S. Pat. No. 3,903,723) comprising a series of roll-forming stands including groups of associated forming members mounted on transverse supporting members and transversely movable under the action of a drive relative to the path of movement of a workpiece to be formed, a device for monitoring the positioning of the workpiece with respect to the path of workpiece movement, arranged at the entry side of the roll-forming machine, and a control unit for controlling the positioning of the groups of forming members with respect to the path of workpiece movement.
In the prior art machine the device for monitoring the positioning of the workpiece is not connected to any means that would be giving information to each roll-forming stand in accordance with the forming pattern. This device can be adjusted for only one configuration of the workpiece. In changing over to another configuration of the workpiece the roll-forming machine is readjusted, while the monitoring of the workpiece of a complicated configuration, for example that with transverse dimensions alternately widening and narrowing, is impossible. The control unit for controlling transverse movement of the forming members comprises a common drive shaft to thereby place limitation on the scope of working of the roll-forming machine primarily because all the clutches and the transverse supporting members, in this instance lead screws, in all the forming stands rotate simultaneously in one and the same direction. Therefore it is possible to process only widening or narrowing workpieces. A workpiece of a complicated configuration can not be roll-formed, otherwise it would be necessary that the lead screws in some roll-forming stands rotate in one direction while in some other roll-forming stands they should rotate in the reverse direction. The prior art arrangement cannot be used in the continuous roll-forming process since the workpiece to be formed must be fed into the roll-forming machine to switch on the limit switch with its leading end and thereby actuate the clutches.
Therefore, since the prior art roll-forming machine is composed of the roll-forming stands each having forming members mounted on plates and the plates, in turn, mounted for transverse movement on screws, a plate is likely to be stuck on the screws due to pitch deviations or cross-threading in operation as a result of irregular loading.
The present invention is directed to offset these difficulties.